Method and apparatus for installing and removing components of an air preheater

ABSTRACT

An access system for installing and removing rotor components of an air preheater includes a lifting beam assembly having a pulley rotatably mounted adjacent to a proximal end portion of the lifting beam. The proximal end portion of the lifting beam and pulley are inserted through an access opening in the preheater housing into the preheater rotor until the proximal end portion of the lifting beam is supported on one of a plurality of radially spaced internal lifting beam supports connected to the rotor post. An external lifting beam support installed externally to the housing supports a distal end portion of the lifting beam. A tugger cable is carried on the pulley and extends along the lifting beam. A proximal end of the tugger cable is mounted to a lifting saddle. A pin inserted through saddle lugs of the lifting saddle and component lugs mounted to the rotor component mounts the lifting saddle to the rotor component.

BACKGROUND OF THE INVENTION

[0001] This invention relates generally to rotary heat exchangers. More particularly, the present invention relates to a method and apparatus for installing and removing components of an air preheater rotor.

[0002] Rotary regenerative air preheaters are commonly used to transfer heat from the flue gases exiting a furnace to the incoming combustion air. A typical rotary regenerative heater has a cylindrical rotor divided into compartments in which are disposed and supported spaced heat transfer plates which, as the rotor turns, are alternately exposed to a stream of heating gas and then upon rotation of the rotor to a stream of cooler air or other gaseous fluid to be heated. As the heat transfer plates are exposed to the heating gas, they absorb heat therefrom and then when exposed to the cool air or other gaseous fluid to be heated, the heat absorbed from the heating gas by the heat transfer plates is transferred to the cooler gas.

[0003] The rotor of most heat exchangers of this type have traditionally been assembled and loaded from overhead, utilizing rigging which is mounted to structures located over the intended position of the air preheater. Such construction is not possible when overhead obstructions exist or when there is insufficient structure to allow overhead rigging. In addition, traditional assembly/loading techniques require personnel to enter or get onto the rotor at various times during the assembly/loading process. Since there are periods of time when the rotor is significantly out of balance, for example when heat transfer baskets are being removed or installed, there is a significant personnel hazard due to the possibility of a rotor coming loose and free-wheeling.

SUMMARY OF THE INVENTION

[0004] Briefly stated, the invention in a preferred form is an access system for installing and removing rotor components of an air preheater. The access system includes a lifting beam assembly having a pulley rotatably mounted adjacent to a proximal end portion of the lifting beam. The proximal end portion of the lifting beam and pulley are inserted through an access opening in the preheater housing into the preheater rotor until the proximal end portion of the lifting beam is supported on one of a plurality of radially spaced internal lifting beam supports connected to the rotor post. An external lifting beam support installed externally to the housing supports a distal end portion of the lifting beam. A tugger cable is carried on the pulley and extends along the lifting beam. A proximal end of the tugger cable may be connected to the rotor component.

[0005] A lifting saddle mounted to the proximal end of the tugger cable may be connected to the rotor component. Multiple component lugs are mounted to the rotor component. The lifting saddle includes a pin and multiple saddle lugs. The axis formed by openings in the component lugs is aligned with the access formed by openings in the saddle lugs and the pin is inserted through the openings of the component and saddle lugs to connect the rotor component to the tugger cable. The lifting saddle also includes a horizontally extending support platform. The saddle lugs are mounted to and extend downwardly from the support platform, with the axis of the saddle lug openings and the lateral centerline of the support platform defining a substantially vertical plane. First and second stiffener bars are mounted to the first and second sides of the support platform, respectively, with the first and second stiffener bars forming a space therebetween. A lifting bar extends across the space at the longitudinal centerline of the support platform and is mounted to the first and second stiffener bars. The proximal end of the tugger cable is mounted to the lifting bar.

[0006] The distal end portion of the lifting beam is received in an opening in the external lifting beam support which extends substantially parallel to the rotor axis. A pin extending transversely through the external lifting beam support and the distal end portion of the lifting beam prevents longitudinal movement of the lifting beam assembly when the tugger cable applies a lifting force to the rotor component.

[0007] It is an object of the invention to provide a new and improved access system for installing and removing rotor components of an air preheater.

[0008] It is also an object of the invention to provide an access system for an air preheater which does not require personnel to enter the rotor during the installation and removal of rotor components.

[0009] Other objects and advantages of the invention will become apparent from the drawings and specification.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present invention may be better understood and its numerous objects and advantages will become apparent to those skilled in the art by reference to the accompanying drawings in which:

[0011]FIG. 1 is a general perspective view of a horizontal rotary regenerative air preheater.

[0012]FIG. 2 is a schematic diagram of an access system in accordance with the invention shown installed in an air preheater for the installation/removal of a single layer of full sector baskets.

[0013]FIG. 3 is an enlarged side view, partly broken away, of the lifting beam assembly of FIG. 2.

[0014]FIG. 4 is a top view of the lifting beam assembly of FIG. 3.

[0015]FIG. 5 is an enlarged side view of the lifting saddle of FIG. 2.

[0016]FIG. 6 is an end view of the lifting saddle of FIG. 5.

[0017]FIG. 7 is a side view of an alternate embodiment of the lifting saddle of FIG. 5.

[0018]FIG. 8 is a schematic diagram of the lifting beam assembly, the lifting saddle, the tugger cable, and a temporary lifting lug installed in an air preheater for the installation of a preassembled rotor compartment.

[0019]FIG. 9 is a schematic diagram of an access system in accordance with the invention shown installed in an air preheater for the installation/removal of two layers of sector baskets.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020]FIG. 1 of the drawings is a partially cut-away perspective view of a typical horizontal air heater showing a housing 12 in which the rotor 14 is mounted on drive shaft or post 16 for rotation as indicated by the arrow 18. The rotor is composed of a plurality of compartments 20 with each compartment containing a full sector heat exchange basket 22 and with each sector being defined by the diaphragms 24. The heat exchange baskets 22 contain the heat exchange surface. The housing 12 is divided by means of the flow impervious sector plate 26 into a flue gas side and an air side. A corresponding sector plate is also located on the other side of the unit. The hot flue gases enter the air heater through the gas inlet duct 28, flow through the rotor where heat is transferred to the rotor and then exit through gas outlet duct 30. The countercurrent flowing air enters through air inlet duct 32, flows through the rotor where it picks up heat and then exits through air outlet duct 34.

[0021] An access system 10 in accordance with the invention is employed to load or unload internal components of the air preheater through the bottom of the air preheater housing 12 rather than from above in the traditional manner. With reference to FIGS. 2 and 9, the access system 10 is comprised of one or two lifting beam assemblies 36, one or two tugger cables 38, multiple internal lifting beam supports 40, one or two external lifting beam supports 42, one or two lifting saddles 44, and component lifting lugs 46. As explained in greater detail below, a single lifting beam assembly 36 providing access through a single access opening 48 is sufficient for the installation or removal of certain rotor components 49 while two lifting beam assemblies 36 providing access through separate access openings 48, 48′ are required for the installation or removal of other rotor components 49.

[0022] Each lifting beam assembly 36 includes a lifting beam 50 having a proximal end portion 52 which is positionable within the rotor 14 and a distal end portion 54 which is positionable in an area 56 outside the rotor 14. The proximal end portion 52 of the lifting beam 50 may be alternately positioned in the rotor 14, to remove or install a component 49, and removed from the rotor 14, to allow rotation of the rotor 14 to access a different compartment 20.

[0023] To install a lifting beam assembly 36, the proximal end portion 52 of the beam 50 is inserted into the rotor 14 through an access opening 48, located in the hot end and/or cold end center section just below the respective support bearings 58, until the proximal end portion 52 is received within and supported by the internal lifting beam support 40, which is mounted to the rotor post assembly 16. The distal end portion 54 of the lifting beam 50 is supported on the external lifting beam support 42, which is located in the area 56 outside of the rotor 14, preferably in an easily accessible location. The final positioning of the lifting beam assembly 36 is determined by the axial length of the rotor component 49, as explained in greater detail below.

[0024] With further reference to FIGS. 3 and 4, a slot 60 extends vertically through a mounting segment 62 of the lifting beam 50 which is adjacent to the proximal end portion 52 of the lifting beam 50. As explained in greater detail below, the rotor component 49 which is to be installed or removed is suspended from a lifting saddle 44 which in turn hangs from a tugger cable 38 carried on a pulley 64 which is rotatably mounted within the slot 60 by a pin 66. Generally, the maximum available headroom for rigging a rotor component 49 to be moved is limited to the radial distance between the rotor post shell 68 and the outboard end 70 of the rotor end plates 72. Pulley 64 minimizes the amount of headroom that is required to rig such a component 49.

[0025] The lifting saddle 44 allows the full sector baskets, rotor compartment sections, or other rotor components to be connected to the tugger cable 38 that runs through the lifting beams integral pulley 64. Lugs 74, 76 on the lifting saddle 44 are temporarily mated to lugs 46 on the rotor component 49 by lining up openings 78, 80 in the lugs 74, 76, 46 and inserting a pin 82 through the openings 78, 78′, 80. For air preheater baskets 22, the lifting lugs 46 are permanently installed on the nose of the baskets 22. When using the subject lifting system to lift rotor compartment sections 84 during rotor construction, temporary lifting lugs 46′ can be installed within the preassembled rotor compartment sections 84, as shown in FIG. 8.

[0026] The lifting saddle lugs 74, 76 are mounted to and extend downwardly from a support platform 86 (FIGS. 5 and 6) such that the axis 88 formed by the openings 78, 78′ in the lifting saddle lugs 74, 76 is parallel to the lateral centerline 90 of the support platform 86 and such that axis 88 and centerline 90 substantially lie on the same vertical plane when the lifting saddle 44 is used to suspend a rotor component 49 from the tugger cable 38. First and second stiffener bars 92, 94 are mounted along the support platform 86, forming a space 96 therebetween. A lifting bar 98 extends across the space 96 at the longitudinal centerline 100 of the support platform/stiffener bar assembly, with the end portions 102 of the lifting bar 98 being mounted to the stiffener bars 92, 94. Attaching the tugger cable 38 to the lifting bar 98 allows rotor components 49 to be picked up from a horizontal face down position without binding the rigging. The stiffener bars 92, 94 may each have an opening 104 for receiving the lifting bar end portions 102. The stiffener bars 92, 94 also provide additional mechanical strength to the lifting saddle 44.

[0027] In FIG. 7, an alternate embodiment of the lifting saddle 44′ is shown having first and second pairs of lugs 74′, 76′. Each rotor component lug 46 is received between the lugs comprising one of the pair of lugs 74′, 76′.

[0028] Preferably, the opening 78′ in one of the lifting saddle lugs 76 has a surface 106 that is threaded and the pin 82 has a threaded end segment 108 such that the pin threaded end segment 108 is inserted through the other lifting saddle lug 74 and the rotor component lugs 46, all of which have unthreaded openings 78, 80, and screwed into threaded opening 78′ to thereby positively lock the pin 82 into place. The unthreaded opening 78 of lifting saddle lug 74 preferably has an inside diameter which is sufficiently greater than the outside diameter of the pin 82 to provide a clearance between the pin 82 and the opening surface to facilitate insertion of the pin 82 during installation. The openings 80 of the rotor component lugs 46 preferably have an inside diameter which is greater than the inside diameter of lug 74 to allow for fouling of the openings 80 during operation of the air preheater.

[0029] To prevent cocking of rotor component 49 during installation/removal, the rotor component 49 is suspended from the lifting saddle 44 and the lifting saddle 44 is mounted to the tugger cable 38 such that the axial centerline 112 of rotor component 49 is substantially coplanar with the lateral centerline 90 of the lifting saddle support platform 86 and the axis 110 of the portion of tugger cable 38 which extends vertically from pulley 64 lies on this common plane. The final positioning of the lifting beam assembly 36 is determined by the axial length of the rotor component 49, which determines the axial centerline 112 of the rotor component 49. The lifting beam 50 is inserted an axial distance D such that the first and second axial ends 114, 116 of the rotor component 49 have sufficient clearance for components of the rotor 14 which have already been installed to provide for free vertical movement of rotor component 49 within the rotor 14. Depending on the configuration of the lifting beam 50 and the rotor 14, an end segment 118 of the proximal end portion 52 may extend axially beyond the internal lifting beam support 40, as shown in FIG. 2.

[0030] The internal lifting beam supports 40 that are part of the rotor post assembly are located between each adjacent stub diaphragm 120 (FIG. 8). These supports 40 each have a single opening 122 extending axially through them to accommodate insertion of the proximal end portion 52 of the lifting beam 50. The opening 122 is sufficiently larger than the beam 50 to ensure that the build up of fly ash and other fouling media do not prevent the lifting beam 50 from being easily inserted. Preferably, the supports 40 are located as close as possible to the lifting beam pulley 64 to minimize beam deflection when the lifting beam 50 is under load. This positioning will also allow traditional end plates 72 to be installed near the air heater center line end of the baskets without interfering with the lifting beam 50.

[0031] In addition to supporting the distal end portion 54 of the lifting beam 50, the external lifting beam support 42 also prevents axial movement of the installed lifting beam 50. The external lifting beam support 42 has a single opening 124 which extends in the axial direction of the rotor 14 for receiving the distal end portion 54 of the lifting beam 50. A pin 126 inserted through aligned holes in the external lifting beam support 42 and the segment of the distal end portion 54 of the lifting beam 50 received in opening 124 prevents the lifting beam 50 from moving axially when the lifting force from a tugger 128 is applied. Transition supports (not shown) may also be used intermediate the proximal and distal end portions 52, 54 of the beam 50 to minimize lifting beam deflection and to facilitate insertion and extraction of the lifting beam 50.

[0032] A single lifting beam assembly 36 is sufficient for installation/removal of baskets in compartments having only a single layer of baskets (FIG. 2). Two lifting beam assemblies 36 are required for installation/removal of baskets in compartments having two layers of baskets (FIG. 9). Similarly, two lifting beam assemblies 36 are required for installation/removal of compartment sections. As shown in FIG. 9, the axis 130 formed by first and second access openings 48, 48′ is substantially parallel to the rotor axis and to the axis 132 formed by the first and second lifting beams 50.

[0033] Basket removal and installation is easy to accomplish with the subject system. Once the lugs 46, 74, 76 of the basket 22 and lifting saddle 44 have been pinned together, the basket 22 can be lowered or raised for removal or installation. During removal, sufficient tension is applied by the tugger cable 38 to allow the basket bolts to be removed. With these bolts removed, the basket 22 can be lowered from the heater through an access hole in the bottom of the air preheater housing 12. During installation, the free hanging baskets self center as they are drawn into the air preheater rotor 14. In addition, the free hanging baskets 22 can be easily jockeyed into position for bolting. Torquing and shimming of the baskets 22 is performed at the 12 o'clock position of the air preheater rotor 14, as in conventional installation procedures.

[0034] There are a number of safety benefits to this method of basket removal and installation. The first is that it is not necessary for personnel conducting the basket change to get into or on the rotor 14 during the basket change process. Since there are periods of time when the rotor 14 is significantly out of balance in any basket installation/removal procedure, this reduces the possibility of serious injury if a rotor 14 should come loose and free wheel. Second, the lifting beam 50 acts as a fail-safe rotor locking mechanism when it is inserted into the rotor 14 during the basket change operation. Finally, hanging baskets 22 by their nose provides greater stability for the baskets than other transport methods which could be utilized for bottom loading of an air preheater. For example, lifting baskets 22 from the bottom with a jacking mechanism leaves the basket unstable, prone to tipping, and difficult to jockey into position for bolting.

[0035] While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation. 

What is claimed is:
 1. An access system for installing and removing rotor components of an air preheater, the rotor components including air preheater baskets and rotor compartments, the air preheater including a rotor and a housing surrounding the rotor, the rotor having a horizontally extending rotor post defining an axis, the housing having oppositely disposed axial end portions, at least one of the axial end portions defining an access opening, the access system comprising: a lifting beam assembly including a lifting beam and a pulley, the lifting beam having oppositely disposed proximal and distal end portions, the pulley being rotatably mounted to the lifting beam adjacent to the proximal end portion, the proximal end portion and pulley being adapted for insertion through the access opening into the rotor; a plurality of radially spaced internal lifting beam supports adapted for connection to the rotor post, a one of the internal lifting beam supports supporting the proximal end portion of the lifting beam; an external lifting beam support adapted for installation externally to the housing, the external lifting beam support supporting the distal end portion of the lifting beam; and a tugger cable carried on the pulley and extending along the lifting beam from a proximal end to a distal end, the proximal end of the tugger cable being adapted for connection to the rotor component.
 2. The access system of claim 1 wherein the lifting beam also has a mounting segment disposed adjacent to the proximal end portion, the mounting segment defining a vertically extending slot, the pulley being rotatably mounted within the slot.
 3. The access system of claim 1 further comprising a lifting saddle mounted to the proximal end of the tugger cable, the lifting saddle being adapted for connection to the rotor component.
 4. The access system of claim 3 further comprising a plurality of component lugs adapted for mounting to the rotor component, wherein the lifting saddle includes a pin and a plurality of saddle lugs, the component lugs and the saddle lugs each defining an opening, the openings of the component lugs defining an axis and the openings of the saddle lugs defining an axis, the axis of the saddle lugs being alignable with the axis of the component lugs and the pin being insertable through the openings of the component and saddle lugs to connect the rotor component to the tugger cable.
 5. The access system of claim 4 wherein the component lugs are adapted for permanent mounting to a nose of an air preheater basket.
 6. The access system of claim 4 wherein the component lugs are adapted for removable mounting in a rotor compartment.
 7. The access system of claim 4 wherein the lifting saddle also includes a horizontally extending support platform defining lateral and longitudinal centerlines, the saddle lugs being mounted to and extending downwardly from the support platform, the axis of the openings of the saddle lugs and the lateral centerline of the support platform defining a substantially vertical plane.
 8. The access system of claim 7 wherein the support platform has oppositely disposed, longitudinally extending first and second sides and the lifting saddle further includes first and second stiffener bars mounted to the first and second sides of the support platform, respectively, the first and second stiffener bars forming a space therebetween.
 9. The access system of claim 8 wherein the lifting saddle further includes a lifting bar extending across the space at the longitudinal centerline of the support platform, the lifting bar being mounted to the first and second stiffener bars, the proximal end of the tugger cable being mounted to the lifting bar.
 10. The access system of claim 4 wherein the opening of a one of the saddle lugs has a threaded surface and the pin has a threaded end segment, the pin threaded end segment engaging the threaded surface of the opening whereby the pin is positively locked to the saddle lug.
 11. The access system of claim 1 wherein each of the internal lifting beam supports defines an opening extending substantially parallel to the rotor axis, the proximal end portion of the lifting beam being received in the opening.
 12. The access system of claim 1 wherein the external lifting beam support defines an opening extending substantially parallel to the rotor axis, the distal end portion of the lifting beam being received in the opening.
 13. The access system of claim 12 further including a pin extending transversely through the external lifting beam support and the distal end portion of the lifting beam.
 14. An access system for installing and removing rotor components of an air preheater, the rotor components including air preheater baskets and rotor compartments, the air preheater including a rotor and a housing surrounding the rotor, the rotor having a horizontally extending rotor post defining an axis, the housing having oppositely disposed axial end portions, at least one of the axial end portions defining an access opening, the access system comprising: a plurality of component lugs adapted for mounting to the rotor component; a lifting beam assembly including a lifting beam and a pulley, the lifting beam having oppositely disposed proximal and distal end portions, the pulley being rotatably mounted to the lifting beam adjacent to the proximal end portion, the proximal end portion and pulley being adapted for insertion through the access opening into the rotor; a plurality of radially spaced internal lifting beam supports adapted for connection to the rotor post, a one of the internal lifting beam supports supporting the proximal end portion of the lifting beam; an external lifting beam support adapted for installation externally to the housing, the external lifting beam support supporting the distal end portion of the lifting beam; a tugger cable carried on the pulley and extending along the lifting beam from a proximal end to a distal end, the proximal end of the tugger cable being adapted for connection to the rotor component; and a lifting saddle mounted to the proximal end of the tugger cable, the lifting saddle being mountable to the component lugs.
 15. An access system for installing and removing rotor components of an air preheater, the rotor components including air preheater baskets and rotor compartments, the air preheater including a rotor and a housing surrounding the rotor, the rotor having a horizontally extending rotor post defining an axis, the housing having oppositely disposed axial end portions, at least one of the axial end portions defining an access opening, the access system comprising: a plurality of component lugs adapted for mounting to the rotor component, each of the component lugs defining an opening, the openings of the component lugs defining an axis; a lifting beam assembly including a lifting beam and a pulley, the lifting beam having oppositely disposed proximal and distal end portions, the pulley being rotatably mounted to the lifting beam adjacent to the proximal end portion, the proximal end portion and pulley being adapted for insertion through the access opening into the rotor; a plurality of radially spaced internal lifting beam supports adapted for connection to the rotor post, a one of the internal lifting beam supports supporting the proximal end portion of the lifting beam; an external lifting beam support adapted for installation externally to the housing, the external lifting beam support supporting the distal end portion of the lifting beam; a tugger cable carried on the pulley and extending along the lifting beam from a proximal end to a distal end, the proximal end of the tugger cable being adapted for connection to the rotor component; and a lifting saddle mounted to the proximal end of the tugger cable, the lifting saddle including a plurality of saddle lugs and a pin, each of the saddle lugs defining an opening, the openings of the saddle lugs defining an axis, the axis of the saddle lugs being alignable with the axis of the component lugs and the pin being insertable through the openings of the component and saddle lugs to connect the rotor component to the tugger cable. 